RetroFIT IQ — Building Performance Diagnostics
Home Health Scan

One Company.
One Process.
One Point of Responsibility.

We investigate, diagnose and verify the real performance of your building — heat loss, condensation, damp, air leakage, soundproofing, ventilation and indoor air quality — all under one accountable team led by a Certified Passive House Designer.

01 · Investigate

We collect measured data — blower door, smoke tracing, thermal imaging and moisture readings. We investigate, we don't guess.

One company. One process. One point of responsibility.

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FLIR thermalBlower doorSmoke testingMoisture meterThermal bridging
Realistic British stone manor house used to demonstrate building-performance diagnostics
FLIR · thermal
18.7%
Moisture
Thermal scanHeat loss detected
Cold surface11.4 °C
Thermal anomalyFlagged
Relative humidityRH 68%
Dew pointRisk
CondensationRisk
Move cursor to rotate · hover the steps below
Certified Passive House Designer
Certified Passive House Designer
Passive House Institute (PHI)
Building Physics Assessment
Thermal · airtightness · moisture
Full House Report
Costed, prioritised findings
Fully Insured
Public liability cover
Why Retrofit IQ Is Different

Most contractors recommend insulation. We predict how your building is expected to perform first.

Most companies offer either a survey or an installation. Retrofit IQ offers a complete, engineering-led building-performance process — and for retrofit projects we can model and predict how the proposed upgrade is expected to perform before a single board goes up.

Step 1
Investigate

Thermal imaging, blower door testing, moisture readings, air leakage checks and ventilation review.

Step 2
Diagnose

We identify the real causes of heat loss, condensation, damp, air leakage, overheating and poor comfort — root cause, not symptoms.

Step 3 · Predict
Predict

Where required, a Retrofit IQ Building Physics Assessment uses advanced building physics modelling — U-values, heat loss, moisture movement, condensation risk, thermal bridges and seasonal performance — carried out by a Certified Passive House Designer before any work begins.

Step 4
Design

We compare retrofit options and recommend the most appropriate insulation or building-fabric upgrade.

Step 5
Remedy

Where Retrofit IQ carries out the works, the upgrade is installed as a joined-up, designed process.

Step 6
Verify

Post-works re-testing against the measured baseline confirms the upgrade performs as designed.

Learn about Building Physics Assessment
Our services — Investigate → Design → Verify

Everything we do is one stage of a single process.

Three connected disciplines, one point of responsibility. Hover or tap a stage to see the services within it.

Explore Investigate
Real Thermal Imaging Findings

The defects we identify — measured, not guessed.

Every image below is from a real RetrofitIQ on-site investigation across London and the South East. We use calibrated FLIR thermal imaging, blower door testing and moisture diagnostics to identify the root cause — then design and remediate the right intervention.

Heat Loss

Large continuous cold surfaces where heat is escaping through walls, floors and roofs faster than the heating can keep up.

Related service
Thermal imaging survey of a cold external door and threshold draught showing a continuous heat-loss areaCold door / draughtView service
12.5–21.2°CInternal face of an external door reading significantly colder than the surrounding walls, with cold air pooling at the threshold — a large continuous heat-loss area and draught path through a poorly insulated door.
FLIR thermal imaging survey of an external wall and ceiling junction showing reduced insulation performanceExternal wall / junctionView service
19.0–24.4°CHeat loss through an external wall section and wall-to-ceiling junction, indicating reduced thermal performance and possible insulation discontinuity.
External thermal imaging survey of a bay window showing heat escaping through the frame and glazingBay window heat lossView service
10.9–19.8°CExternal thermal imaging showing elevated surface temperatures around the bay window frame and glazing, indicating heat escaping from the property through the window assembly and reducing overall energy efficiency.
Air Leakage

Cold air drawn through gaps, joints and service penetrations — revealed under depressurisation during blower door testing.

Related service
Air leakage at unsealed pipe and cable service penetrations through an external wall, found during testingService penetrationsView service
Unsealed service penetrations where gas pipes, electrical cable entries and utility services pass through the external wall near ground level — creating significant uncontrolled air leakage pathways between the inside and outside of the building.
Smoke testing revealing air escaping around the roof windows as well as the eaves and roof perimeter — uncontrolled airEaves & rooflineView service
Smoke testing revealing air escaping around the roof windows as well as the eaves and roof perimeter — uncontrolled air leakage where the ceiling and loft space meet the external wall head and roofline.
Smoke testing revealing air-leakage paths around a bay window perimeter and frame junctionsBay window perimeterView service
Smoke testing confirming multiple leakage paths around the bay window perimeter, frame junctions, floor vent area and an existing unsealed opening — uncontrolled air movement at the structural junction between the bay and the main wall.
Thermal Bridging

Localised cold paths where the building structure bypasses the insulation layer — lintels, reveals, slab edges and corners.

Related service
Thermal imaging survey showing a thermal bridge along a wall-to-ceiling junction and cornerWall/ceiling junctionView service
18.9–23.1°CCold band tracking the wall-to-ceiling junction and down the corner, indicating a geometric thermal bridge caused by reduced insulation continuity at the building junction.
FLIR thermal imaging showing dot-and-dab plasterboard insulation discontinuity and cold areasDot-and-dab discontinuityView service
18.1–24.2°CThermal pattern consistent with dot-and-dab plasterboard installation, showing insulation discontinuity and possible air movement behind the plasterboard, creating localised cold areas and increased condensation risk.
Thermal imaging survey showing reduced insulation continuity and a thermal bridge at a wall perimeterReduced insulation continuityView service
17.2–22.2°CThermal image indicating reduced insulation continuity at the wall perimeter, creating a localised thermal bridge and increased heat loss through the building envelope.
Missing Insulation

Large continuous cold zones — typically lofts, eaves and dwarf walls — where insulation has slumped, gone missing or was never installed.

Related service
Thermal imaging survey of a cold wall behind furniture consistent with missing or insufficient insulationCold wall behind furnitureView service
17.2–27.9°CLarge continuous cold wall area behind furniture, significantly cooler than the surrounding internal surfaces. This pattern is consistent with reduced thermal performance within this external wall section, possibly caused by missing, displaced or insufficient insulation. Restricted air movement behind furniture can further reduce surface temperature and increase the risk of condensation.
FLIR thermal imaging of a cold wall below a window beside a radiator, indicating missing insulationCold wall below windowView service
16.3–58.6°CExtensive cold zone below the window, immediately beside the radiator. Despite local heat input, this wall section remains significantly colder than adjacent surfaces, indicating poor thermal performance and likely missing or insufficient insulation beneath the window area.
Thermal imaging survey showing a localised cold spot at a wall-to-ceiling junction from an insulation defectLocalised cold spotView service
12.0–18.5°CLocalised cold patch at the wall-to-ceiling junction, with surface temperatures dropping to approximately 12.7°C while surrounding areas remain significantly warmer. The shape and temperature difference are consistent with a local insulation defect, missing insulation, displaced insulation or a significant thermal bridge within the building envelope.
Condensation Risk

Surfaces measured below the room's dew point — the locations where condensation, black mould and damp are most likely to recur.

Related service
Thermal imaging of a cold wall-to-ceiling corner identified as the main condensation and mould-risk areaCold corner / condensation riskView service
13.9–27.6°CCold wall-to-ceiling junction and corner with significantly reduced surface temperatures. Following insulation improvements elsewhere, this area has become the coldest remaining surface within the room and is now acting as the primary condensation and mould-risk location. This illustrates how condensation can migrate to the next coldest surface once the original thermal defect has been improved.
Moisture meter recording elevated readings on a wall consistent with condensation riskElevated moistureView service
Elevated moisture meter readings compared with surrounding areas, consistent with prolonged exposure to condensation risk.
Moisture meter recording elevated readings within damaged plaster from repeated condensationElevated moistureView service
Elevated moisture meter readings recorded within the damaged plaster area, consistent with prolonged exposure to condensation risk and repeated moisture accumulation.
Moisture-Related Defects

Cooler surface signals corroborated with moisture-meter readings — helping separate condensation from rising or penetrating damp.

Related service
Thermal imaging beside a window showing a cool damp signature used to target moisture-meter readingsDamp signatureView service
16.3–20.4°CThermal imaging beside the window showing a cooler band across the wall surface — a temperature signature consistent with surface moisture and evaporative cooling, used to target follow-up moisture-meter readings.
Imaging moisture meter recording a high reading in blown, deteriorated plaster beside a windowHigh moisture readingView service
Imaging moisture meter recording a high reading of 35.4 within blown, deteriorated plaster beside the window — confirming significant moisture present within the wall fabric.
Damp investigation showing plaster and finish deterioration linked to elevated moisture readingsMoisture-related surface damageView service
Visible deterioration of plaster and decorative finishes adjacent to the affected area. The observed damage correlates with both the thermal anomaly and elevated moisture readings recorded during the investigation.

Surface temperatures captured with a calibrated FLIR thermal imaging camera under stabilised conditions. Investigate → Diagnose → Design → Remediate → Verify.

The RetrofitIQ approach

One company. One process. One point of responsibility.

Most retrofit and building-performance projects involve multiple companies — an assessor, a designer, a contractor and a separate verifier. That creates communication gaps, conflicting advice and poor outcomes when no one owns the result end-to-end.

Industry standard

4 companies, 0 owners.

  • ×
    Assessor — spots symptoms
  • ×
    Designer — specifies without site context
  • ×
    Contractor — installs to a different brief
  • ×
    Verifier — tests after the fact

Gaps between stages. Nobody answerable for the final result.

RetrofitIQ model

Investigate → Diagnose → Design → Install → Verify

  • ✓
    Investigate — FLIR thermal imaging, blower door, smoke tracing, moisture mapping.
  • ✓
    Diagnose — Root cause — not symptoms.
  • ✓
    Design — Site-aware spec by a Certified Passive House Designer.
  • ✓
    Install — Our own trained team — no subcontracted gaps.
  • ✓
    Verify — Post-works re-test against measured baselines.

Single point of responsibility. One signature from problem to verified result.

Book a diagnostic survey See real investigations
Retrofit IQ Academy

The building science behind every survey — explained.

In-depth, plain-English guides written by a Certified Passive House Designer — covering Passive House, airtightness, moisture, thermal imaging, ventilation, retrofit and acoustics. Explore the full library inside the Academy.

Browse the full Academy
Customer Feedback

Verified reviews from Checkatrade and MyBuilder.

Real reviews from real homeowners, landlords and tenants — left directly on our public Checkatrade (3 reviews) and MyBuilder (5 reviews) profiles. Each card preserves the original customer text and adds a short professional summary of the project completed.

CT
Checkatrade
View profile →
MB
MyBuilder
View profile →
CTVerified on Checkatrade
Soundproofing — acoustic floor build-up across multiple rooms + wall upgrade
N17, London · Posted June 2026
“Excellent Service. Highly recommended. The work was done to perfection. We were always kept informed of what was happening and given advice of the best cost effective option. Anyone who choses this company will not be disappointed. They are extremely professional and good value for money. We will be using them again to do some more work. Thank you GAS.”
Project summary

Whole-floor acoustic upgrade across multiple rooms in an N17 home — existing finishes stripped, RW5 acoustic mineral wool installed between joists, decoupling treatment applied to the floor structure, new floorboards laid, acoustic underlay + new carpet finished. One bedroom received an additional acoustic wall upgrade. Outcome: a measurably quieter home and a 10/10 review.

Verified Checkatrade customer
CTVerified on Checkatrade
Underfloor insulation
E17, London · Posted 05 April
“George was brilliant. We required the existing floor to be lifted and insulation installed. Throughout the process George was tidy, considerate and offered advice on how to achieve the best outcome. The team documented the process throughly with photos for my records. I would definitely use GAS again for similar works or general construction in our home.”
Project summary

Suspended-timber underfloor insulation upgrade — lifted finished floor, installed continuous insulation between joists, fully documented with photographs. Outcome: warmer floors, reduced heat loss and a clean, well-documented retrofit the client is happy to reuse.

Luke Large
CTVerified on Checkatrade
Property assessment & costed improvements report
IG8, London · Posted 13 March
“George was friendly, arrived on time and was very helpful during the assessment. He answered all of my questions and showed a passion for what he does. The report provided was very thorough and George was able to provide full costings for all proposed improvements to my flat. I highly recommend him!”
Project summary

Whole-flat Home Health Diagnostic assessment with a thorough written report and a fully-costed schedule of improvement options. Outcome: clear evidence-based plan the client can prioritise and budget against.

Verified Checkatrade customer
CTVerified on Checkatrade
Multi-trade renovation works (occupied property)
SG6 · Posted 06 February
“Very professional, communicated clearly throughout the project, and paid close attention to detail. We were moving in the middle of the works, while also working from home, and George made sure to always work around us, prioritise things that would help us and keep things tidy in the house. Very knowledgeable and friendly, already booked for more projects!”
Project summary

Sensitive multi-trade renovation programme delivered while the client was moving in and working from home. Outcome: minimal disruption, tidy site, and a relationship strong enough that the client booked further works.

Verified Checkatrade customer
MBVerified on MyBuilder
Investigation of moisture / paint swelling around internal window
Orpington · 17 Feb 2026
Project summary

Diagnostic investigation of moisture and paint swelling around an internal window reveal. Surface moisture, dewpoint and thermal imaging used to identify the source (cold reveal + interstitial condensation) and recommend a remediation plan.

MyBuilder user from Orpington
MBVerified on MyBuilder
Replace insulated ventilation duct hose in loft
Greenwich, London · 10 Feb 2026
Project summary

Replaced a damaged insulated ventilation duct hose in the loft, restoring efficient warm-air movement, preventing condensation inside the duct and protecting the loft insulation from moisture damage.

MyBuilder user from Greenwich, London
More feedback

See the full set of verified reviews.

All reviews
Reviews & Trust

Rated 5 / 5 by verified customers.

9 verified reviews on Checkatrade & MyBuilder

Measurement-based building diagnostics, not guesswork. Read our verified reviews, find us on Google, and if we’ve worked with you we’d be grateful for a review — it helps future clients know exactly what to expect.

Read our reviews View us on Google Leave a Google reviewRequest an assessment
Book with confidence
  • Certified Passive House Designer (PHI)
  • Fully insured · public liability cover
  • 5 / 5 average across 9 verified reviews
  • Practical building-envelope experience
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5 Signs Your Home Is Losing
Energy, Comfort and Indoor Air Quality.

A diagnostics-led guide for homeowners, landlords, architects and property managers — by a Certified Passive House Designer. Includes the five Passive House principles and our five-step Building Performance Diagnostics process.

01Excessive Heat Loss
02Air Leakage & Draughts
03Condensation & Mould Growth
04Poor Ventilation & Indoor Air Quality
05Thermal Bridges & Cold Surfaces
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